#include <iostream>

using namespace std;

class const_class
{
private:
    int sum;

    constexpr int calc_sum(int n) const
    {
        return n == 1 ? 1 : n + calc_sum(n - 1);
    }

public:
    constexpr const_class(int n):sum(calc_sum(n))
    {
    }

    constexpr get_sum() const
    {
        return sum;
    }
};


int main()
{
    constexpr const_class c(10);
    cout<<c.get_sum()<<endl;
}